The decreasing trend of total ozone in Taipei is presented, analyzed and discussed. Seasonal trends of the total column ozone show that winter has the sharpest decreasing trend in the past. Summer shows the slightly increasing trend from the TOMS data. The result from trend analysis of total ozone levels provides the information for the estimation of UV-B reached the surface in Taipei. The UV-B model predicts that the future increasing exposure of UV-B due to the decreasing ozone level varies dependent upon the legislation enacted in Taiwan.